A method for promoting surface reconstruction on perovskite based on deep passivation

Abstract

The application relates to the technical field of solar cells, in particular to a method for promoting surface reconstruction of a perovskite based on deep passivation, which comprises the following steps: (1) cleaning a transparent conductive layer to obtain a clean transparent conductive substrate; preparing a first carrier transport layer on the transparent conductive substrate to obtain a substrate; (2) preparing a perovskite layer on the substrate; (3) after depositing a passivation layer on the perovskite layer, sequentially executing three annealing procedures including forward annealing, reverse annealing and forward annealing again to form a surface passivation structure; and (4) preparing a functional layer on the passivation layer, wherein the functional layer is composed of a second carrier transport layer and an electrode layer. By introducing a sequential annealing step in the passivation process, the volatilization rate of a solvent is effectively delayed, the residual solution in the passivation agent is utilized to expand the surface passivation depth of the perovskite, the passivation effect is strengthened, the secondary crystallization of the perovskite surface is promoted, and finally the performance of a perovskite solar cell device is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a method for promoting perovskite surface reconstruction based on deep passivation. Background Technology

[0002] Perovskite solar cells have become a research hotspot in the photovoltaic field due to their high photoelectric conversion efficiency and low manufacturing cost. However, perovskite materials contain a large number of defects on their surface and at grain boundaries (such as uncoordinated Pb). 2+ Defects such as lead ions and halogen vacancies act as non-radiative recombination centers. Charge carriers (electron-hole pairs) recombine prematurely at these defects, leading to a shortened carrier lifetime and ultimately significantly reducing the photoelectric conversion efficiency and long-term stability of the battery. To reduce defects, a passivation strategy is typically employed, which involves coating the perovskite surface with passivating agents (such as organic ammonium salts or polymers) to passivate uncoordinated lead ions or halogen vacancies.

[0003] Traditional processes typically employ a single annealing method with the active side facing upwards. In this method, the solvent in the passivation layer evaporates too quickly, making it difficult for the passivating agent molecules to fully penetrate into the deep defect sites of the perovskite layer. Only shallow surface defects can be passivated, resulting in a limited passivation effect. At the same time, the excessively rapid solvent evaporation causes uneven distribution of the passivating agent, affecting the integrity and coverage of the passivation layer, further restricting the improvement of battery performance.

[0004] Therefore, optimizing the annealing process and precisely controlling the diffusion behavior of the passivating agent to enhance the depth of action and uniformity of the passivating agent in the perovskite film has become one of the key issues to overcome the performance bottleneck of perovskite solar cells and promote their industrialization. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of the prior art and provide a method for promoting perovskite surface reconstruction based on deep passivation. By introducing a sequential annealing process of "forward-reverse-reforward", the evaporation rate of the passivation layer solvent is slowed down, the residual passivating agent is used to extend the passivation reaction depth of the perovskite surface, and the secondary crystallization of the perovskite surface is promoted to achieve surface reconstruction. Ultimately, this enhances the passivation effect, improves the quality of the perovskite film, and significantly improves the device performance of perovskite solar cells.

[0006] The above objectives are achieved through the following technical solutions:

[0007] A method for promoting perovskite surface reconstruction based on deep passivation, the method being used to fabricate perovskite solar cells, the perovskite solar cells comprising, from bottom to top, a transparent conductive layer, a first carrier transport layer, a perovskite layer, a passivation layer, a second carrier transport layer, and an electrode layer, the method comprising the following steps:

[0008] Step (1): Clean the transparent conductive layer to obtain a clean transparent conductive substrate; fabricate the first carrier transport layer on the transparent conductive substrate to obtain a substrate;

[0009] Step (2): Prepare a perovskite layer on the substrate;

[0010] Step (3): After depositing a passivation layer on the perovskite layer as the active surface, perform three annealing processes in sequence: forward annealing, reverse annealing, and forward annealing again.

[0011] The forward annealing specifically involves placing the substrate with the perovskite layer directly on a heating stage, ensuring that the active surface faces upwards and the bottom of the substrate is in contact with the surface of the heating stage, so that the heat from the heating stage is conducted to the active surface through the substrate.

[0012] The reverse annealing specifically involves placing the active surface downwards and facing the heating table;

[0013] The reverse annealing step enables active control of the orientation of the active surface, prolongs the solvent evaporation time of the passivation layer, promotes the penetration and diffusion of passivating agent molecules into the interior of the perovskite layer, and ultimately forms a surface passivation structure with optimized interface characteristics, thereby achieving the reconstruction of the perovskite upper surface.

[0014] Step (4): A functional layer is prepared on the passivation layer, the functional layer being composed of the second carrier transport layer and the electrode layer.

[0015] As a further optimization of this method, the cleaning treatment of the transparent conductive layer in step (1) is specifically as follows: the transparent conductive layer is ultrasonically cleaned in the corresponding solvents in the order of acetone, IPA (isopropanol), acetone, and IPA for 20 min, then dried at 65 °C, and finally subjected to ultraviolet ozone treatment for 15 min to obtain the transparent conductive substrate.

[0016] As a further optimization of this method, the transparent conductive layer is one of FTO (fluorine-doped tin oxide) glass, ITO (indium tin oxide) glass, AZO (aluminum-doped zinc oxide) glass, transparent silver nanowire glass, transparent copper nanowire glass, transparent polyaniline glass, and flexible transparent substrate.

[0017] As a further optimization of this method, the method of preparing the perovskite layer in step (2) includes any one or a combination of at least two of spin coating, blade coating, slot coating, spraying, and screen printing.

[0018] As a further optimization of this method, the general structural formula of the perovskite layer material in step (2) is ABX3;

[0019] Among them, A is selected from CH3NH3 + (MA + ), CH(NH2)2 + (FA + ), Rb + or Cs + or a combination of any one or at least two of them;

[0020] B is selected from Pb 2+ , Ge 2+ , Sn 2+ or a combination of any one or at least two of them;

[0021] X is selected from Cl - , Br - or I - or a combination of any one or at least two of them.

[0022] As a further optimization of this method, the material of the perovskite layer is selected from any one of the following:

[0023] Conventional bandgap perovskite: including MAPbI3, FAPbI3, MA x FA (1-x) PbI3 (0<x<1), Cs x MA y FA z PbI3 (x+y+z=1), the bandgap width range is 1.49 eV - 1.75 eV;

[0024] Wide bandgap perovskite: including Cs x MA y FA z PbI 3-n Br n (x+y+z=1, 0<n<3); the bandgap width range is 1.60 eV - 1.8 eV;

[0025] Narrow bandgap perovskite: including Cs x MA y FA z Sn n Pb 1-n I3 (x+y+z=1, 0<n<1); the bandgap width range is 1.20 eV - 1.50 eV;

[0026] The thickness range of the perovskite layer is 100 nm - 1000 nm.

[0027] As a further optimization of this method, in the three annealing procedures in step (3), the first forward annealing time ranges from 1 s to 60 s, the second reverse annealing time ranges from 1 min to 10 min, the third forward annealing time ranges from 1 min to 30 min, and the temperature range for all three annealing processes is 50 ℃ to 200 ℃.

[0028] As a further optimization of this method, the solvent of the passivation layer in step (3) is any one or a combination of at least two of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), isopropanol (IPA), ethyl acetate, anisole, ethanol, ethylene glycol methyl ether, acetonitrile, and chlorobenzene.

[0029] As a further optimization of this method, the environmental atmosphere for preparing the passivation layer in step (3) includes dry air or nitrogen, and the thickness of the passivation layer is 1 nm-100 nm.

[0030] As a further optimization of this method, in the annealing process of step (3), the contact mode between the active surface and the heating table includes any one of complete contact, gradient contact, suspended placement, and porous support frame support.

[0031] This invention provides a method for promoting perovskite surface reconstruction based on deep passivation, specifically utilizing multi-directional annealing technology to precisely control the diffusion behavior of the passivating agent on the perovskite surface. This method effectively solves the key problem of insufficient passivating agent penetration depth in traditional passivation processes by alternating annealing orientations to prolong solvent evaporation time, significantly improving the passivation effect on the perovskite surface. The process is simple and controllable, exhibiting excellent compatibility with current mainstream perovskite device fabrication processes, providing a reliable technical solution for the industrial production of high-performance perovskite solar cells. Core advantages and technical features include:

[0032] (1) Precise control of the diffusion depth of the passivating agent: By introducing a sequential annealing process design and controlling the evaporation of the solvent, the penetration depth of the passivating agent in the perovskite phase is significantly improved, and the effective passivation of deep defects is achieved.

[0033] (2) Comprehensive enhancement of defect passivation effect: The multi-directional annealing process promotes the uniform distribution and deep penetration of passivating agent molecules on the perovskite surface, thereby significantly improving the coverage and depth of the passivation layer. This process effectively reduces defects such as uncoordinated ions at the surface and grain boundaries, and suppresses non-radiative recombination losses.

[0034] (3) Synergistic optimization of device performance parameters: The perovskite solar cell prepared by this method has achieved a significant improvement in photoelectric conversion efficiency. The performance improvement is due to the enhanced passivation effect. At the same time, key performance parameters such as open-circuit voltage, short-circuit current density and fill factor have been optimized.

[0035] (4) Excellent process compatibility and scalability: This technical solution can be directly integrated into existing perovskite solar cell fabrication processes. Its operation is simple, requiring no complex equipment modifications, and it has a wide process window. These characteristics collectively endow this method with outstanding industrial application value, providing a reliable technical solution for promoting the large-scale production of perovskite solar cells. Attached Figure Description

[0036] Figure 1 This is a flowchart of a method for promoting perovskite surface reconstruction based on deep passivation, as described in this invention.

[0037] Figure 2 The diagram shows the conversion efficiency of perovskite solar cells when the volume percentage of DMSO in the passivating agent solvent component is 0.1% (Example 1), 0.5% (Example 1), 1% (Example 1), 2% (Example 1), 5% (Example 1), and 10% (Example 1) respectively in the method for promoting perovskite surface reconstruction based on deep passivation according to the present invention.

[0038] Figure 3 To compare the perovskite passivation layer prepared by the conventional method under the optimal conditions of the method for promoting perovskite surface reconstruction based on deep passivation described in this invention (Example 2) with that prepared by the conventional method (Comparative Example 1), they were applied to single-junction perovskite solar cells respectively, and statistical data comparison charts of their open-circuit voltage, short-circuit current, fill factor and power conversion efficiency were obtained.

[0039] Figure 4 This is a comparison of the current density-voltage curves of the optimal perovskite preparation conditions (Example 2) and the conventional preparation method (Comparative Example 1) obtained by the method for promoting perovskite surface reconstruction based on deep passivation described in this invention. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. The described embodiments are merely some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] like Figure 1As shown, this scheme provides a method for promoting perovskite surface reconstruction based on deep passivation, used to fabricate perovskite solar cells consisting of a transparent conductive layer, a first carrier transport layer, a perovskite layer, a passivation layer, a second carrier transport layer, and an electrode layer, from bottom to top. The specific steps are as follows:

[0042] Step (1): Clean the transparent conductive layer to obtain a clean transparent conductive substrate; fabricate the first carrier transport layer on the transparent conductive substrate to obtain a substrate. This step specifically includes:

[0043] Step (101): Cleaning of the transparent conductive layer:

[0044] The transparent conductive layer serves as the current-collecting substrate for the battery, and its surface cleanliness directly affects the adhesion and interfacial resistance of subsequent film layers. The specific cleaning process is as follows: The transparent conductive layer (such as FTO glass, ITO glass, etc.) is ultrasonically cleaned for 20 minutes in each of the corresponding solvents in the order of acetone, IPA (isopropanol), acetone, and IPA. Acetone effectively removes surface organic contaminants, while IPA dissolves residual acetone and reduces water stains; this alternating cleaning ensures thorough removal of impurities. After cleaning, the transparent conductive layer is dried at 65°C to remove residual solvents. Finally, a 15-minute ultraviolet ozone treatment is performed. Ultraviolet irradiation generates ozone, which oxidizes and removes trace organic contaminants from the surface and increases the number of surface hydroxyl groups, improving the film quality of the subsequent first carrier transport layer. After the above treatment, a clean transparent conductive substrate is obtained.

[0045] Step (102): Fabrication of the first carrier transport layer:

[0046] The core function of the first carrier transport layer is to selectively transport carriers (e.g., the hole transport layer transports holes, and the electron transport layer transports electrons), achieving separation of electrons and holes generated in the perovskite layer, while reducing interface defects between the transparent conductive substrate and the perovskite layer. The first carrier transport layer (e.g., using the self-assembled molecule MeO-2PACz as the hole transport layer) is prepared on a clean transparent conductive substrate using methods such as spin coating or blade coating, forming the substrate of the transparent conductive substrate and the first carrier transport layer.

[0047] Step (2): Prepare a perovskite layer on the substrate.

[0048] The perovskite layer is the core light-absorbing layer of a solar cell. It generates electron-hole pairs by absorbing photons from sunlight. Its material composition and crystal quality directly determine the cell's light absorption efficiency and carrier generation capability.

[0049] In this step, the material selection for the perovskite layer has the general structural formula ABX3.

[0050] Among them, A is selected from CH3NH3 + (MA + ), CH(NH2)2 + (FA + ), Rb + or Cs + , or a combination of any one or at least two of them;

[0051] B is selected from Pb 2+ , Ge 2+ , Sn 2+ , or a combination of any one or at least two of them;

[0052] X is selected from Cl - , Br - or I - , or a combination of any one or at least two of them.

[0053] In this step, for the specific material classification, the material of the perovskite layer is selected from any one of the following:

[0054] Conventional bandgap perovskite: including MAPbI3, FAPbI3, MA x FA (1-x) PbI3 (0 < x < 1), Cs x MA y FA z PbI3 (x + y + z = 1), the bandgap width ranges from 1.49 eV to 1.75 eV, and the thickness ranges from 100 nm to 1000 nm.

[0055] Wide bandgap perovskite: including Cs x MA y FA z PbI 3-n Br n (x + y + z = 1, 0 < n < 3), the bandgap width ranges from 1.60 eV to 1.8 eV, and the thickness ranges from 100 nm to 1000 nm;

[0056] Narrow bandgap perovskite: including Cs x MA y FA[[ID=6​​​​​​​The film formation process in this step includes: preparing the perovskite layer using a solution method, specifically one or a combination of spin coating, blade coating, slot coating, spraying, and screen printing. Spin coating is suitable for small-area preparation in the laboratory; blade coating and slot coating are suitable for large-area industrial production. The thickness of the perovskite layer is controlled between 100 nm and 1000 nm: too thin a layer will result in insufficient light absorption, while too thick a layer will increase the carrier transport distance and make recombination more likely.

[0058] Step (3): After depositing a passivation layer on the perovskite layer as the active surface, perform three annealing processes in sequence: forward annealing, reverse annealing, and forward annealing again.

[0059] The forward annealing specifically involves placing the substrate with the perovskite layer directly on a heating stage, ensuring that the active surface faces upward and the inactive surface (such as the transparent conductive layer side) is in contact with the surface of the heating stage, so that the heat from the heating stage is conducted to the active surface through the substrate and preferentially acts on the passivation layer.

[0060] The reverse annealing specifically involves: flipping the substrate that has undergone the first forward annealing by 180° so that the active surface (the surface where the passivation layer is located) faces down and the inactive surface faces up, with the active surface facing the heating stage; it should be noted that the contact methods between the active surface and the heating stage include, but are not limited to, complete contact, gradient contact, suspended placement, and support by a porous support frame, with a 0-5mm gap maintained between the active surface and the heating stage.

[0061] The reverse annealing step enables active control of the orientation of the active surface, prolongs the solvent evaporation time of the passivation layer, promotes the penetration and diffusion of passivating agent molecules into the interior of the perovskite layer, and ultimately forms a surface passivation structure with optimized interface characteristics, thereby achieving the reconstruction of the perovskite upper surface.

[0062] This step involves uniformly depositing a passivating agent solution onto the perovskite layer, followed by a sequential annealing process. First, the active side is annealed upwards to remove some of the solvent. Then, the active side is annealed downwards to promote the penetration and diffusion of passivating molecules into the perovskite layer. Finally, the active side is annealed three times upwards. This effectively passivates defect states on the perovskite surface and at grain boundaries, reduces carrier recombination losses at the interface, and improves the environmental stability of the perovskite film (such as resistance to humidity and oxygen corrosion).

[0063] Specifically, in the annealing process, the first forward annealing time ranges from 1 s to 60 s, the second reverse annealing time ranges from 1 min to 10 min, the third forward annealing time ranges from 1 min to 30 min, and the annealing temperature ranges from 50 ℃ to 200 ℃.

[0064] As an optimization of this step, during the passivating agent annealing process, the first annealing time is 60 s, the second annealing time is 10 min, the third annealing time is 30 min, and the annealing temperature is 200 ℃.

[0065] As a further explanation of this step:

[0066] The passivation layer solvent is any one or a combination of at least two of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), isopropanol (IPA), ethyl acetate, anisole, ethanol, ethylene glycol methyl ether, acetonitrile, and chlorobenzene.

[0067] The environmental atmosphere for preparing the passivation layer includes, but is not limited to, dry air and nitrogen.

[0068] The thickness of the passivation layer is 1 nm to 100 nm.

[0069] In the annealing process, the contact methods between the active surface and the heating table include, but are not limited to, complete contact, gradient contact, suspended placement, and support by a porous support frame.

[0070] Step (4): A functional layer is fabricated on the passivation layer. The functional layer consists of the second carrier transport layer and the electrode layer. Its main function is to extract and transport carriers to form a complete external circuit path.

[0071] The methods for preparing the perovskite layer and other functional layers on the substrate mentioned above include, but are not limited to, spin coating, blade coating, slot coating, spraying, and screen printing.

[0072] It should be noted that the types of perovskite solar cells in this scheme include single-junction perovskite solar cells, as well as the perovskite layer fabrication of the wide-bandgap perovskite portion in perovskite / crystalline silicon tandem solar cells; it also includes perovskite / perovskite tandem solar cells, which serve as the perovskite layers for wide-bandgap and narrow-bandgap cells, respectively.

[0073] The passivation layer prepared by this method is used in perovskite solar cells not only in the various single-cell cells of different perovskites mentioned above, but also in the light-absorbing layer of the wide-bandgap cell in the all-perovskite tandem cell. The structure of the all-perovskite tandem cell is conductive glass / carrier transport layer / wide-bandgap perovskite / carrier transport layer / intermediate layer / carrier transport layer / narrow-bandgap perovskite layer / carrier transport layer / electrode.

[0074] The perovskite layer prepared by this method also includes a light-absorbing layer for the narrow bandgap cell in a full perovskite tandem solar cell. The full perovskite tandem solar cell structure is: conductive glass / carrier transport layer / wide bandgap perovskite / carrier transport layer / intermediate layer / carrier transport layer / narrow bandgap perovskite layer / carrier transport layer / electrode.

[0075] The perovskite layer prepared by this method is used in perovskite solar cells, which also include a light-absorbing layer for wide bandgap cells in perovskite / crystalline silicon tandem solar cells. The perovskite / crystalline silicon solar cell structure is crystalline silicon cell / intermediate layer / carrier transport layer / wide bandgap perovskite / carrier transport layer / electrode.

[0076] Example 1:

[0077] This embodiment provides a method for promoting perovskite surface reconstruction based on deep passivation, including the following steps:

[0078] Step (1): Substrate pretreatment

[0079] Operational details: The ITO or FTO substrate glass was ultrasonically cleaned in the order of acetone → IPA → acetone → IPA, each cleaning cycle lasting 20 min. After cleaning, it was dried at 65 °C and then treated with ultraviolet ozone for 15 min to obtain a clean, transparent conductive layer substrate. The self-assembled molecular material MeO-2PACz (concentration 0.75 mg / mL) was dissolved in ethanol to prepare a hole transport layer precursor solution.

[0080] Film formation process: Take 65 μL of precursor solution, spin coat at 5000 rpm for 20 s, and then anneal at 100 ℃ for 10 min (annealing environment is air).

[0081] Step (2): Preparation of perovskite perovskite layer

[0082] Material composition: The chemical formula of the perovskite material is Cs. 0.05 MA 0.05 FA 0.90 PbBr 0.1 I 2.9 A 1.4 M precursor solution was prepared by mixing CsI, FAI, MABr, MACl, PbBr2 and PbI2 in a DMF:DMSO mixed solvent (volume ratio 4:1).

[0083] Additive modification: Add 10 mol% MACl, 1 mg / mL GuaBCI, 1 mg / mL LPMACI and 2 mg / mL PbCl2 to the precursor solution and stir for more than 6 h.

[0084] Film formation process: 65 μL of solution was dropped onto the hole transport layer, and the film was first spin-coated at 1000 rpm for 5 s, then at 5000 rpm for 30 s. Finally, 120 μL of chlorobenzene was added as an antisolvent within the last 15 s. The perovskite film was then annealed at 110 ℃ for 20 min.

[0085] Preparation of the passivation layer: 1 mg / mL PDAI2 was dissolved in a mixed solvent of IPA and DMSO (DMSO volume percentages were 0.1%, 0.5%, 1%, 2%, 5%, and 10%, respectively). The passivation solution was spin-coated onto the perovskite layer at 5000 rpm for 20 s, followed by sequential forward annealing for 6 s, reverse annealing for 2 min, and forward annealing again for 8 min.

[0086] Step (3): Fabrication of functional layer

[0087] Materials and Processes: The sample was transferred to a thermal evaporator and processed in a high vacuum environment (<5×10⁻⁶). -5 At Pa), a 18 nm thick layer of fullerene (C) was deposited by thermal evaporation. 60 As an electron transport medium, electrons generated by the perovskite layer are selectively extracted. A 20 nm thick layer of SnO2 is then deposited under high vacuum as a buffer layer between the electron transport layer and the electrode, optimizing energy level matching and preventing electrode material diffusion. Finally, an 80 nm thick layer of copper (Cu) is thermally evaporated and deposited as the electrode, forming a complete current collection path.

[0088] Example 2:

[0089] This embodiment provides a perovskite solar cell, which differs from Embodiment 1 above only in that the volume percentage of DMSO is fixed at 0.5%, while the other materials, structures, experimental parameters, and preparation methods are the same as in Embodiment 1.

[0090] Comparative Example 1:

[0091] This embodiment provides a perovskite solar cell, which differs from Embodiment 2 in that, after spin-coating a passivating agent onto the perovskite layer, only forward annealing is performed, and the annealing time is the same as the total annealing time in Embodiment 2. Other materials, structures, experimental parameters, and preparation methods are the same as in Embodiment 2.

[0092] Performance testing

[0093] like Figure 2 As shown, the performance of a single-junction perovskite solar cell fabricated using a deep passivation-driven perovskite surface reconstruction technique was investigated. Analysis revealed that the cell's power conversion efficiency is significantly dependent on the DMSO volume fraction. Specifically, the cell's power conversion efficiency reaches its peak when the DMSO volume fraction is set to 0.5%. This phenomenon clearly indicates that there is an optimization range for the DMSO volume fraction, and in this study, 0.5% is the optimal value for this parameter.

[0094] Figure 3The data further clarifies that setting the volume percentage of DMSO in the passivating agent solvent to 0.5% significantly and comprehensively improves various key photovoltaic performance parameters of perovskite solar cells, including open-circuit voltage, short-circuit current density, fill factor, and ultimately, power conversion efficiency. This performance improvement is mainly attributed to the optimization effect of sequential annealing, which slows down solvent evaporation and utilizes the residual solution in the passivating agent to extend the passivation reaction depth on the perovskite surface. This method effectively enhances the passivation effect and promotes secondary surface crystallization, thereby improving film quality and enhancing the device performance of perovskite solar cells.

[0095] Figure 4 The current density-voltage characteristic curves of Example 2 (using an optimized annealing process with a DMSO volume fraction of 0.5%) and Comparative Example 1 (using a conventional annealing method without reverse annealing) are compared. Quantitative analysis shows that the highest power conversion efficiency of the device in Example 2 reached 24.52%, an improvement of 2.89 percentage points compared to Comparative Example 1. This significant efficiency improvement directly confirms that the perovskite layer prepared by the optimized process effectively enhances both the thin film crystal quality and photoelectric properties.

[0096] The above description is merely illustrative of the embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for promoting surface reconstruction on perovskite based on deep passivation, characterized in that, The method is used for preparing a perovskite solar cell, the perovskite solar cell comprising a transparent conductive layer, a first carrier transport layer, a perovskite layer, a passivation layer, a second carrier transport layer and an electrode layer from bottom to top, the method comprising the following steps: Step (1): cleaning treatment is performed on the transparent conductive layer to obtain a cleaned transparent conductive substrate; the first carrier transport layer is prepared on the transparent conductive substrate to obtain a substrate; Step (2): the perovskite layer is prepared on the substrate; Step (3): after the passivation layer is deposited on the perovskite layer as an active surface, a three-time annealing procedure of forward annealing, reverse annealing and forward annealing again is sequentially performed; The forward annealing is specifically as follows: the substrate with the prepared perovskite layer is directly placed on a heating table, the active surface is ensured to face upward, the bottom of the substrate is in contact with the surface of the heating table, and the heat of the heating table is conducted to the active surface through the substrate; The reverse annealing is specifically as follows: the active surface faces downward and faces the heating table; The active surface orientation is actively controlled through the reverse annealing step, the solvent volatilization time of the passivation layer is prolonged, the penetration and diffusion of the passivation agent molecules to the inside of the perovskite layer are promoted, finally, a surface passivation structure with optimized interface characteristics is formed, and the upper surface of the perovskite is reconstructed; Step (4): a functional layer is prepared on the passivation layer, and the functional layer is composed of the second carrier transport layer and the electrode layer.

2. The method according to claim 1, wherein, In step (1), the cleaning treatment performed on the transparent conductive layer is specifically as follows: the transparent conductive layer is subjected to ultrasonic cleaning in corresponding solvents in the order of acetone, IPA, acetone and IPA for 20 min, then dried at 65 ℃, and finally subjected to 15 min ultraviolet ozone treatment to obtain the transparent conductive substrate.

3. The method of claim 1 or 2, wherein the method is based on deep passivation to promote surface reconstruction of perovskite. The transparent conductive layer is one of FTO glass, ITO glass, AZO glass, transparent silver nanowire glass, transparent copper nanowire glass, transparent polyaniline glass and flexible transparent substrate.

4. The method of claim 1, wherein the method is characterized by, In step (2), the preparation method of the perovskite layer includes any one or a combination of at least two of spin coating, blade coating, slot coating, spraying and screen printing.

5. The method of claim 1, wherein the method is based on deep passivation to promote surface reconstruction of perovskite. In step (2), the material of the perovskite layer has a general structure of ABX3. wherein A is selected from any one or a combination of at least two of CH3NH3 + (MA + ), CH(NH2)2 + (FA + ), Rb + , or Cs + . B is selected from any one or a combination of at least two of Pb 2+ , Ge 2+ , Sn 2+ . X is selected from any one or a combination of at least two of Cl - , Br - , or I - .

6. The method according to claim 5, wherein the method is characterized by, The material of the perovskite layer is selected from any one of the following: Conventional bandgap perovskites: including MAPbI3, FAPbI3, MA x FA (1-x) PbI3 (0 < x < 1), Cs x MA y FA z PbI3 (x + y + z = 1) with a bandgap in the range 1.49 eV - 1.75 eV; Wide bandgap perovskites: including Cs x MA y FA z PbI 3-n Br n (x+y+z = 1, 0 < n < 3); band gap ranges from 1.60 eV - 1.8 eV; Narrow band gap perovskite: including Cs x MA y FA z Sn n Pb 1-n I3 (x+y+z=1, 0<n<1); band gap ranges from 1.20 eV - 1.50 eV; The thickness of the perovskite layer ranges from 100 nm to 1000 nm.

7. The method of claim 1, wherein the method is based on deep passivation to promote surface reconstruction of perovskite. In the three-time annealing procedure of step (3), the first forward annealing time ranges from 1 s to 60 s, the second reverse annealing time ranges from 1 min to 10 min, the third forward annealing time ranges from 1 min to 30 min, and the temperature range of the three-time annealing is 50 ℃-200 ℃.

8. The method of claim 1, wherein the method is based on deep passivation to promote surface reconstruction of perovskite. In step (3), the solvent of the passivation layer is any one or a combination of at least two of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), ethyl acetate, anisole, ethanol, ethylene glycol methyl ether, acetonitrile and chlorobenzene.

9. The method of claim 1, wherein the method is based on deep passivation to promote surface reconstruction of perovskite. The environment atmosphere for preparing the passivation layer in step (3) includes dry air or nitrogen, and the thickness of the passivation layer is 1 nm-100 nm.

10. The method of claim 1, wherein the method is based on deep passivation to promote surface reconstruction of perovskite. In the annealing process of step (3), the contact mode of the active surface with the heating table includes any one of full contact, gradient contact, suspended placement, and support by a porous support frame.

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